The present invention concerns a process for running an anionically or cationically catalytically accelerated gas phase reaction, a process for running catalytically accelerated gas phase polymerization, as well as applications of the process and polymerizates produced according to the process of the invention.
The catalysts in anionically or cationically catalytically accelerated gas phase reactions or in a reactor with a wet suspension are generally arranged on supports and enclosed on this account.
In the case of catalysts arranged on supports for running so-called heterogeneous catalysis, the support together with catalyst is held in the gaseous reaction mixture by means of a fluidized bed. Especially in polymerization in the gas phase, like production of polyolefins, catalysts arranged on supports are used in which so-called metallocene-based catalysts have recently come into use, which are arranged on silica gel or magnesium chloride as support particles, among other things. The major advantage of these catalysts based on metallocene compounds is that selective or controlled reactions are made possible and production of polymers with substantially improved properties relative to now common polymers is made possible, especially in terms of elasticity, heat deflection temperature, hardness, etc.
However, the production of such cataysts based on the metallocene compounds is still very costly and intricate in that the substance forming the catalyst must initially be deposited on the support and then activated, for example, by alkylation agents or with so-called Lewis acids. However, production of the corresponding polymers, like polyolefins, based on such metallocene catalysts, is therefore also very expensive.
When ionic catalysts dissolved in solvents are used, there is a problem that the reaction rate must generally be adversely affected by the presence of a solvent and the counterion. Moreover, the solvent can partially react with the catalyst or form complexes by addition to the active anion and cation so that the activity of the catalyst is reduced. In addition, the solvent destroys favorable electrostatic interaction that exists in the gas phase. These catalysts are generally so-called Ziegler-Natta catalysts and catalysts appropriate for running so-called metathesis processes.
It is therefore a task of the present invention to propose a process by introducing anionic or cationic catalysts to a gas phase reaction mixture for catalytic acceleration of the reaction without the drawbacks just described.
This task is solved according to the invention by a process according to the wording, especially of claim 1.
It is proposed that the active anion or active cation that forms the catalyst be introduced as a free anion or cation without a corresponding counterion, as well as at least largely free of any solvent, into the gaseous reaction mixture.
According to one variant it is proposed that the substance forming the catalyst initially be activated introduced or dissolved in a solvent and the solvent as well as the counterion then largely eliminated before introduction to the gaseous reaction mixture.
Introduction of an anion or cation without a corresponding counterion and essentially solvent-free is possible by introducing the catalyst to the gaseous reaction mixture by electrospray ionization, thermospray ion vaporization or with so-called atmospheric pressure ionization.
So-called Ziegler-Natta catalysts or metallocene catalysts that are initially dissolved and activated in an appropriate solvent are suitable in particular as catalysts. Spraying of the so dissolved and activated catalyst then occurs by electrospray, thermospray or ion vaporization or by atmospheric pressure ionization, in which case spraying generally occurs under high pressure with simultaneous enclosure of the spray cloud in an inert gas, like nitrogen or a noble gas. By heating and application of a vacuum at least part of the spray solvent is eliminated and the counterion corresponding to the catalyst is eliminated by application of an electrical potential or electrical voltage. The anion or cation now so isolated, which serves the reaction as catalyst, is then introduced to a reaction space in which the gaseous reaction mixture or the gaseous monomer to be polymerized is arranged. It is then possible to arrange several reaction stages or spaces in succession in order to run consecutive, chain-forming polymerization reactions, especially in the case of polymerization.
Because of this relatively simple production of extremely efficient anionic or cationic catalysts (i.e., with 106-107 times higher reactivity) for catalytic acceleration of gas phase reactions it becomes possible, for example, to make the still costly but technically superior metallocene-based polyolefin production process cheaper and in fact in a cost range corresponding to that of linear high-density polyethylene and polypropylene production processes. The production process cost difference is now no longer a result of the difference in production of the catalyst, but merely the difference in production of the monomer.
Similarly favorable results can generally be achieved in gas phase reactions accelerated with Ziegler-Natta catalysts and ring opening metathesis polymerization reactions in the gas phase, in which cationic catalysts are generally used. Simple polymerization of, say, gas phase olefin monomer molecules can be induced by electrospray or ion vaporization of the catalyst.